Bit-stock.



Patented June 25, l90l. H NEWS BET SWQK (No Model.)

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NITED STATES PATENT QFFICE- IIERMANN FUCHS, OF GERA, GERMANY, ASSIGNOR TO WESSELMAN BOHRER COMPANY, OF GERA-ZWGTZEN, GERMANY.

BIT-STOCK.

SPECIFICATION forming part of Letters Patent No. 677,198, dated June 25, 1901.

Application filed January 8, 1901. Serial No. 42,515. (No model.)

To all wh m i may OOH/067%: gagement with a thread cut in the stock, Beit known that I, HERMANN FUCHS, a subwhile it carries the jaw C along by extending ect of the Emperor of Germany, residing at thereinto.

Gera, Germany, have invented new and use- If the screw-spindle is rotated once, then ful Improvements in Bit-Stocks, of which the thejawB would,if the spindle E were preventfollowing is a specification. ed from longitudinal movement, be moved Thejaws of chucks generally used for holdin or out by the thread end- F the extent of ing the boring-tool are simultaneously opened one pitch thereof; but as the screw-spindle E and closed, so that the chuck will serve for by threaded end G engages the chuck A the to holding tools of differentthickness in the dispindle at the same time by one rotation is dis- 6o rection of their length. For setting the jaws placed the extent of one pitch of the screw end of the chuck a right and left hand screw- G, carrying along the jaw G the same exthread is employed, so that the rotation of tent. The jaw B is thus displaced with rethe screw one way or the other secures the spect to onejawC the difference between the 15 desired setting or movement of the jaws. pitches of the two thread ends F and G. If Such an adjusting device has, however, a disthe pitch of thread end G is onehalf that of advantage in that the jaw-compressingpower thread F, the jaw B is displaced a distance is comparatively small, and as a matter of equal to one-half that of the pitch of thread fact it is difficult to secure firm hold for the F- that is, one pitch of thread G; but thejaw 2o tool in the chucks in use. This objection is C is also displaced a like extent as it is carto be removed by the present diiferential ried along by thread end G. stock, in which ajaw-actuating screw-spindle By employing a screw-spindle of equal pitch is employed, which is provided with threads and with right and left hand threads the tool, running in like direction, but which threads asa matter of fact, cannot thus far he clamped 25 have varying pitch, one of the threads being sufficiently tight. The same consequently in engagement with one of the jaws and the slips somewhat in the chuck, with the result other with the stock. that the jaws wear, the slipping of the bit in This invention is set forth in the following the chuck becomes worse, and the wear of the specification and claim, and illustrated in the stock-jaws more irregular, so that presently 3o annexed drawings, in which the bit no longer runs centrally, which defect 86 Figure 1 is an elevation of the stock. Fig. is transferred in worse degree to the work. 2 is a plan view of Fig. 1. Fig. 3 is a longi- In tightening the double-threaded screwtudinal section of Fig. 1. Fig. 4 is a transspindle the bending strain is also so great verse section of Fig. 1. that there is risk of breakage. All these ob- 3 5 In the chuck Aareinserted jaws B and C, as jections are obviated by the differential bitknown, their movement being limited by the chuck. The lateral pressure exerted by the ring D. The screw-spindleE serves for movjaws on the thread of the screw-spindle is ing the jaws with respect to one another. It considerably less, as here the thread end F is threaded at its forward part F and at its engages the jaw B; but the other thread end 4o rear part G. Afour-cornered ornon-circular G engages the chuck A. The strain on the 0 hole H allows the insertion of a key I. The screw-spindleE thus approaches or is nearly thread of the screw-spindle E runs in the axial. At the same time as the power resame direction; but the pitch of the thread quired for turning the screw-spindle is less end at F in the example shown is as large the quadrangle Bis spared and worn less than 45 again as that of the thread end at G. The in the chucks thus far in use. former is only in engagement with the jaw \Vhat I claim as new, and desire to secure B, and at this part the chuck is not threaded, by Letters Patent, isso that the screw-spindle is merely guided A chuck including a body having internal by the stock. The end G of the spindle, with jaws slidable toward and from each other,

50 lesser pitch on the other hand, is only in eneach jaw having a side recess, one recess being threaded and the other plain, the chuck abie means on the body for limiting the move- 10 adjacent to the plain recess being threaded, ment of the jaws. a spindle projecting into said body having In testimony whereof I have hereunto set two threaded portions of different pitch, one my hand in the presence of two subscribing threaded portion being set into the plain rewitnesses. cess and engaging the threaded surface on I HERMANN FUCHS.

the body and the other threaded portion be- XVitnesses: ing set into the threaded recess and engag- M. STENDINK, ing the threaded surface thereof, and detach- A. BRAUTIGAM. 

